Menstrual Pain Associated with Brain Changes

New research suggests that when compared to women who do not suffer from cramping, the brains of women who suffer from menstrual cramps are reshaped, with some areas larger, and some smaller in size.

“Our results demonstrate that abnormal (gray matter) GM changes were present in (primary dysmenorrhea)PDM patients even in the absence of pain. This shows that not only sustained pain, but also cyclic occurring menstrual pain can result in longer-lasting central changes,” according to Dr. Jen-Chuen Hsieh, of the National Yang-Ming University in Taipei.

Primary dysmenorrhea (PMD), painful menstruation that is not caused by another gynecological condition, affects 20 to 90 percent of healthy young women. In addition to cramping pain, PMD can also lead to increased sensitivity to any type of pain.

The brain is composed primarily of gray matter and white matter. Gray matter is the body of the nerve cell. White matter consists of the the fiber component of the nerve cell that connects the bodies of the cells, allowing them to communicate.

To investigate the effect of painful menstruation on brain structure, Hsieh and her team used voxel-based morphometry (a type of brain scan), to compare different areas of gray matter in the brains of 32 women with PMD, and compared them to the brains of women without PMD.

All of the women were near the age of 24, and the scans were obtained during a time when the women were not menstruating.

The researchers found that there were decreases in the size of the gray matter in areas of the brain involved in pain transmission, higher level sensory processing, and mood regulation. There was an average increase in the sizes of the areas of the brain that are involved in pain regulation, and in regulating certain hormones. “These changes may underpin a combination of impaired pain inhibition, increased pain facilitation and increased affect,” writes Hsieh.

In addition, the more severe the PMD, the greater the changes seen in the brain. It is not clear whether these changes help in controlling pain, or make it worse.

Some women are severely affected by PMD, and lose time from work or school. Pain can be reduced by many at-home therapies such as exercise, relaxation, diet, and heating pads. Treatment may also include medications such as anti-inflammatories, antidepressants, birth control pills, and prescription pain relievers.

Increased activity of the hormone prostaglandin, which is produced in the uterus, is thought to be a factor in primary dysmenorrhea, and may increase pain levels.

Chronic pain is known to cause functional changes in the structure and function of the nervous system, but these results are new in that “our findings highlight that longer lasting central changes may occur not only in sustained chronic pain conditions but also in cyclic occurring pain conditions,” says Hsieh. Further research may shed light on whether these changes occur as a result of the pain, or as a cause.

“The next step would be to conduct studies to see what role hormones play in these changes, and to determine whether or not the gray matter changes are reversible,” the researchers write.

Hsieh’s results can be found in the September edition of the journal Pain